Centrifugal pump



Jan. 27, 1970 w H. H. HOWARD 3,491,695

CENTRIFUGAL PUMP Filed Oct. 11, 1968 2 Sheets-Sheet 1 Fig./

Henry H. Howard 1N VENTOR.

Jan. 27, 1970 H. H. HOWARD 5 CENTR-IFUGAL PUMP Filed Oct. 11. 1968 2 Sheets-Sheet 2 Henry H. Howard 1 N VENTOR.

3,491,696 CENTRIFUGAL PUMP Henry H. Howard, 2201 Kiernan Ave., Modesto, Calif. 95350 Filed Oct. 11, 1968, Ser. No. 766,829 Int. Cl. F04d 13/12, 29/18, 29/02 U.S. Cl. 103-88 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates generally to centrifugal pumps and more particularly to centrifugal pumps of the sanitary type conventially utilized for the movement of liquid and semiliquid food products, chemicals and the like. More specifically, the present invention relates to the: provision of an improved impeller means for centrifugal pumps of the aforementioned type.

It is an object of the present invention to provide an improved construction for a' centrifugal pump, of the sanitary type, having a multi-stage impeller means.

A further object of the present invention is to provide a novel impeller means for centrifugal pumps comprising a dual stage impeller preferably provided with three impeller lobes in each impeller stage.

Still another object of the present invention is to provide a centrifugal pump means, suitable for use in conjunction with conventional prime mover means, wherein the novel construction thereof results in significantly improved performance whereby the pump is essentially self-priming and does not normally require a positive inlet head pressure whereby the improved pump can be characterized as a semi-positive centrifugal pump.

Still another object of the present invention is to provide a centrifugal pump of the sanitary type wherein the improved construction thereof enables the pump to pass nonfluid foreign matter without sustaining sufiicient damage to the components thereof whereby an emergency shutdown of the pump would be required.

Still another object of the present invention is to provide an improved construction for a centrifugal pump of the sanitary type including a dual-stage impeller means, and pump housing therefor, that can be readily assembled and disassembled for cleaning thereof, and wherein the dual-stage impeller is formed of a relatively rigid synthetic resin.

Still another object of the present invention is to provide an improved centrifugal pump including a dualstage impeller means, including three impeller lobes in each stage, and wherein the lobes of one stage are olfset from the lobes of the second stage.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a perspective view of an exemplary embodiment of a centrifugal pump constructed in accord- United States Patent 3,491,696 Patented Jan. 27, 1970 See ance with the present invention further showing the exemplary pump mounted on an exemplary prime mover;

FIGURE 2 is an enlarged vertical cross-sectional view of the centrifugal pump of FIGURE 1 taken substantially along the plane of the line 22 of FIGURE 1;

FIGURE 3 is a partially exploded perspective view of the centrifugal pump of FIGURE 1 showing certain details of the interior of the pump;

FIGURE 4 is an enlarged side elevational view of the multi-stage impeller means of the exemplary pump illustrated;

FIGURE 5 is a front elevational view of the exemplary multi-stage impeller means; and

FIGURE 6 is a radially extending longitudinal crosssectional view, in somewhat reduced scale, of the impeller means of FIGURE 5 taken upon the section line 6-6 of FIGURE 5, which section line passes medially through two adjacent impeller lobes.

Referring now to the drawings in greater detail, an exemplary embodiment of a centrifugal pump means constructed in accordance with the present invention is indica'ted generally at 10 which for purposes of illustration is only shown as operatively mounted on a conventional drip-proof electric motor 12, comprising an exemplary prime mover. The centrifugal pump means 10 is operatively and concentrically mounted relative to an output shaft 14 of the motor 12 by a generally cylindrical motor adapter means 16 including a normally disposed disk portion 18 releasably or otherwise secured to the motor 12, such as by the through-bolts thereof, not shown. The motor adapter means 16 further includes a centrally apertured disk 20 for releasable, or quick-coupling of the pump means 10 to the motor adapter means 16. As seen best in FIGURE 2, the centrally disposed aperture, indicated generally at 22, in the disk 20 is concentrically disposed relative to the output shaft 14 of the motor 12. In addition, the motor adapter means 16 includes an adapter stub shaft 24 concentric with the motor shaft 14 and normally non-rotatably, and releasably, secured thereto such as by lock means exemplified by the setscrews 26. The adapter stub shaft 24 includes a forwardly disposed portion projecting a substantial distance through the aperture 22 and threaded adjacent the outwardly disposed end thereof as indicated generally at 28. As seen in FIGURES 1, 2 and 3 the disk 20 of the motor adapter means 16 is provided with means for quick-coupling the pump means 10 to the motor adapter means 16 as exemplified by the quick-release holddown bolt means indicated generally at 30 generally comprising three or more such holddown means generally equidistantly spaced about the periphery of the disk 20 which may include suitable apertured radially extending lugs for carrying the holddown bolt means 30. The aforedescribed motor adapter means 16 and adapter stub shaft 24 merely comprise an exemplary means of mounting the pump means 10 to the prime mover 12 and in normal utilization of the pump means 10 the aforedescribed elements remain secured to the prime mover 12. Accordingly, it will be appreciated that the constructional details of the motor adapter means 16 and the adapter stub shaft 24 are selectively modified as may be necessitated by the type of prime mover utilized.

Referring now in greater detail to the constructional details of the exemplary embodiment 10 of a centrifugal pump constructed in accordance with the present invention, the elements thereof shall be described in an exemplary sequence of assembling the pump means 10 relative to the motor adapter means 16 and threaded adapter stub shaft 24 for securement thereto by the holddown bolt means 30. Accordingly, a pump backing plate 32 of generally disk-like configuration includes a rearwardly projecting dished portion 34 apertured as at 36 for the non-engaging through passage of the adapter stub shaft 24, which dished portion 34 provides a seal-receiving recess indicated generally at 38. The backing plate 32 further includes a circumferential groove as indicated at 40 in communication with the peripheral and axial faces of the forward edge portion of the plate 32 for the reception of a resilient seal member as exemplified by the O-ring seal 42 such as formed by neoprene, for example, and retained on the plate 32 in an arcuate land continuously extending about the circumferential junction of the surfaces defining the groove 40. A rotary seal member 44, such as formed of a relatively rigid resin of high lubricity, i.e., a polytetrafluoroethyleneacetyl resin for example, is provided for maintaining a rotary seal between the contiguous faces of the dished portion 34 of the backing plate 32 and the seal member 44. In addition, the seal member 44 is provided with a resilient O-ring seal member 46 received in an annular groove on the inner bore thereof for sealingly receiving the seal member 44 on the adapter stub shaft 24 for rotation therewith. In addition, means, in the form of a helical spring 48, is provided for maintaining the seal 44 in sealing engagement with the dished portion 34 of the backing plate 32.

The spring 48 is compressed at such time as a multistage impeller means indicated generally at 50, and comprising a salient aspect of the present invention, is operatively positioned, i.e., releasably secured to the threaded portion 28 of the adapter stub shaft 24. The configuration of the multi-stage impeller means 50 can be best appreciated from a simultaneous consideration of FIG- URES 3-6 wherein it will be seen that the multi-stage impeller means 50 preferably comprises a dual-stage impeller having a minor diameter first stage impeller as indicated generally at 52 and a major diameter second stage impeller as indicated generally at 54, which impeller stages 52 and 54 are contiguous, i.e., integral. The first stage impeller 52 includes a plurality of lobes 56, which in the embodiment 50 illustrated comprises three lobes 56 equidistantly and radially disposed about a longitudinal axis as indicated at 58. The major diameter second stage 54, as in the case of the minor diameter stage 52, comprises a complementary number, three, of lobes 60 equidistantly, and radially disposed, about the axis 58. As seen best in FIGURE 5, the radially extending longitudinal axes of the first stage lobes 56, as indicated by the phantom line 62 in FIGURE 5, are ofiset from the radially extending longitudinal axes of the major diameter lobes 60 indicated by the phantom line 64 in FIGURE 5. Preferably, and as illustrated, the axes '62 are offset from the axes 64 an amount equaling one half the number of the degrees between adjacent axes 64, which in the exemplary embodiment 50 illustrated comprises an offset of 60.

As seen best in FIGURE 6 the impeller means 50, such as formed of polytetrafluoroethylene, nylon, etc., is axially bored and threaded as indicated at 66, on the rear thereof, for threadably engaging the impeller means 50 on the adapter stub shaft 24 for rotation of the impeller means 50 in a counterclockwise direction about the axis 58, as viewed in FIGURE 5. From a further consideration of FIGURE 6 it will be seen that the major diameter impeller stage 54 can be characterized as being generally cylindrical and the minor diameter impeller stage 52 can be characterized as a truncated hyperbola when considering the geometric configuration of a radially disposed longitudinally extending cross-sectional view through two adjacent lobes of the major and minor impeller stages 54 and 52, respectively. In FIGURE 5, keeping in mind the counterclockwise location thereof, it will be seen that the leading edges 68 of the minor diameter lobes 56 are convex and the trailing edges 70 are concave whereby the geometric configuration of the corner edge 72 created by the truncated forward surface of the minor diameter impeller stage 52 forms a sinuously continuously line wherein that portion of the edge line 72 associated with the rearwardly disposed concave portion of the lobe 56 is concave and the portion of the edge line 72 associated with the leading edge of an adjacent lobe 56 is convex. Simultaneously considering FIGURES 4 and 5, it will be seen that both the leading and trailing edges 74 and 76, respectively, of the major diameter impellers 60 are generally concave and accordingly the corner edge 78 of the major diameter impeller stage 54 comprises a generally constant radius when considering adjacent leading and trailing edges of adjacent lobes 60.

As seen best in FIGURE 5 the leading edges of the major diameter impeller lobes 60 are arcuately relieved as indicated generally at 80 and the step between the generally cylindrical major diameter stage 54 and the generally truncated hyperbola minor diameter stage 52, and particularly the leading edge of the step, is offset approximately 15 counterclockwise from the axis 64, which arcuate displacement is reckoned from the axis 58. In addition, and again reckoning from the axis 58, the outwardly disposed portion of the leading edge of the minor diameter lobes 56 as indicated generally at 82 is displaced approximately 60 from the axis 64. The aforedescribed configuration of the impeller means 50 has been found to provide a highly efficient centrifugal pump means which creates a sufficiently negative pressure at the inlet 84 of its associated pump casing 86 to enable the pump so provided to be characterized as a semi-positive centrifugal pump capable of pumping generally liquid fluent materials from a reservoir not providing a positive static head at the inlet 84. In addition, the smooth curvature of the impeller lobes effect smooth movement of the product being pumped and provides generally higher discharge head pressures than impellers provided heretofore of generally the same radius operating at comparable r.p.m.

Referring now in greater detail to the pump casing 86, and as best seen from a simultaneous consideration of FIGURES 1, 2 and 3, it will be seen that the casing 86 includes a generally tubular portion 88 for the major diameter stage 54 and sized so as to provide a relatively close tolerance between the outer edge portions of the major diameter lobes 60 and wherein an exemplary clearance is in the order of .03 inch. The tubular portion -88 of the casing 86 is provided with a radially extending circumferential flange 90 for releasably securing the casing 86 to the adapter disk 20 with the pump backing 32 retained therebetween in sealed relation thereto by the O-ring 40. The casing 86 is further provided with an inward step 92 complementary to the step between the major diameter stage 54 and the minor diameter stage 52 and wherein the clearance between the step 92 and the impeller means 50 is preferably in the order of 0.3 inch. The casing 86 further includes a generally frusto-conical forward portion 94 for the minor diameter impeller Stage 52, the forward portion of which carries the axial intake 84. As seen best in FIGURES 1 and 3, a generally tangentially disposed outlet is provided on the portion 88 of the casing 86. It will be appreciated that the outlet 85 may be selectively positioned at any point 360 about the axis of the pump by selectively locking the casing 86 with the outlet 85 in the desired position. Although not specifically stated heretofore it will also be appreciated that the clearance between the frusto-conical portion 94 0f the casing 86 and the minor diameter impeller stage 52 is also preferably in the order of .03 inch.

What is claimed as new is as follows:

1. A pump comprising a multi-stage impeller means having at least a minor diameter impeller stage and a major diameter impeller stage, each of said impeller stages having three equidistantly spaced impeller lobes, each of said lobes of said minor diameter impeller stage having a convex leading surface and a concave trailing surface, the convex leading edge surface of a minor diameter lobe being sinuously continuous with the concave trailing edge surface of an adjacent minor diameter lobe, each of said lobes of said major diameter impeller stage having concave leading and trailing edge surfaces, the concave leading edge surface of a major diameter lobe being arcuately continuous with the concave trailing edge surface of an adjacent major diameter lobe, and the radially extending longitudinal axes of said minor diameter lobes being circumferentially disposed intermediate of the radially extending longitudinal axes of said major diameter lobes, and a casing encircling said impeller, said casing including an axial inlet means and a generally tangential outlet means.

2. .The combination of claim 1 wherein the radially extending longitudinal cross-sectional configuration of adjacent lobes of said minor diameter impeller stage is characterized as being a truncated hyperbola, the base of which hyperbola is contiguous with the major diameter impeller stage.

3. The combination of claim 1 wherein the radially extending longitudinal cross-sectional configuration of adjacent lobes of said major diameter impeller stage is characterized as being a cylinder.

4, The combination of claim 1 wherein said multi-stage impeller is formed of a synthetic resin having a low coefficient of friction.

References Cited UNITED STATES PATENTS 619,736 2/1899 Edwards 1031 15 897,397 9/1908 Pirkl 103-103 1,514,293 11/1924 Lawaczeck 103-88 1,763,595 6/1930 Paatsch 103l 15 2,407,748 9/1946 Schmidt 103-403 2,784,673 3/ 1957 Namur 1031 11 2,880,676 4/1959 SIlCCOp 103-114 2,903,971 9/1959 Collins 103-114 3,295,456 1/1967 Warren 103103 HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 

